Recent content by Michael

I have the SCSI2SD internal SSD emulator as a hard drive. I have 2 partitions on it. ID 0 for the boot partition, ID 7 for the 2nd partition (I could change it to ID 1 as an experiment). The Zip is set to ID 5 (hardware switch). All verified in SCSI Probe. Both devices are terminated.  The Zip...

Sybil update: After a few days of sometimes it boots, sometimes not, I found a glitch. The computer won't boot with the SCSI Zip drive attached from a cold startup (switch on). With the Zip drive unattached, it boots every time. If I attach the Zip drive after it boots and do a warm restart, a...

Battery is brand new. 3.6 volts. All the voltages across the power supply check out (12v and 5v). I could check the voltages on the scope for stability and make sure I'm not getting crappy, irregular power, but everything appears to be working fine-- the CRT, the drive lights, the fan. I'd think...

Yep, as predicted. Question mark of doom this morning.  I think I'm going to name this computer "Sybil" because it's got multiple personalities. 

Here's where my ignorance takes over... What am I measuring? Voltage across the trace? Or just basic connectivity looking for a broken trace? I assume the board is not powered for this.  In other news, the computer booted up fine today after my SCSI inspection. I did hit the pins with DeOxit...

Found the schematic for the SCSI chain. It's definitely not SCSI pins. Damn. I got contact between the pins, the external port, and UI12 pins. Working upstream from here. 

Another thought-- I wonder if I have a break in the connection to one of the SCSI pins. The drive does sit there and flash like it's trying to be read. There's no apparent break visually, but I'd swear a light tap on the case seemed to get the thing past the flashing disk drive once in a while...

Each pin through the Ohm meter on my Fluke 87 multimeter. Positive on the pin, to ground on the chassis. 

When I first saw this issue with the original caps installed a month ago, I, too, assumed the hard drive was failing. I first replaced the hard drive from my warehouse garage with another. The problem replicated with a different drive installed. Changed the SCSI cable. Changed the power cable to...

UPDATE: I got the exact same readings as the first time. To the 10'th. Somethin's not right.

Great tip. I will check it out next time.  After working perfectly for 8 hours last night (I threw everything I could at the computer to test it), I fired it up this morning-- got the chime-- and it won't budge past the question mark floppy. It was doing this before I did the cap service, too...

 UPDATE: Well... It appears to have self-corrected. Perhaps there was some residual moisture somewhere causing a glitch. It's been up and running for a few hours now. Zero glitches. The problem was the dirty board. A trip through the dish washer fixed 'er up. This was a neat project. Along the...

Maybe I spoke too soon. It's crashing intermittently. Extremely unstable. That same original pattern comes back now and again. I probably have to work those grounding issues.  Even some bongs of death. Seemingly random.  I'll run the traces to the ROM chips and look for an odd break. Any other...

You guys rock.  I still haven't cleared all the grounding on the bourns chips, but clearly things have taken a turn for the better.

Unless it was leftover flux that flowed around. It looked just awful.